The present invention relates to electronic musical instrumentation and, more particularly, to a musical instrument in which physical sound-producing channels are shared between virtual channels corresponding to different musical components of the accompaniment.
A number of systems have been proposed for providing accompaniment to the playing of a musical instrument, such as an organ. A rather successful scheme is disclosed in U.S. Pat. No. 4,433,601, issued to Hall, et al. for "Orchestral Accompaniment Techniques." In the patented system, accompaniment is provided for a plurality of "musical styles" selectable by a player. The accompaniment contains chordal, bass and percussion lines integrated together in prescheduled sequences of musical events and stored in tabular form. When a harmony is selected by the player, an appropriate set of instructions is processed sequentially to sound the accompaniment. Harmonies produced by the accompaniment depend upon player input, but the sequences themselves cannot be altered from their prescheduled form.
Another form of automatic accompaniment is disclosed in the above-referenced U.S. patent application Ser. No. 274,606. The art existing prior to the method of that application was capable of embellishing a melody by adding notes limited to the chosen harmony notes sounded a preselected musical compass below the melody. Such art was unable to produce fill notes, which were not tones of the harmony recognized by the instrument. This is a drawback when musicians of limited ability and/or dexterity seek to sustain the accompaniment by playing a minimum number of harmony notes. The invention of the referenced application incorporates significant aspects of musicianship into the automated instrument art by providing a system in which fill notes are derived on the basis of the harmonic relationship between a played melody and a recognized chord. Harmonization is achieved through the use of tabular listings of notes which are not limited to the recognized chord. Data storage requirements are minimized through a system of accompaniment note identification based upon musical transposition.
Most prior art organs achieve multiple voicing by applying signals to a plurality of hardware channels dedicated to individual components of the music. Sound producing channels were assigned when the instrument was registered and did not vary as a function of the musical input. The instrument of U.S. Pat. No. 4,433,601 went beyond the prior art by sharing sound producing channels among the notes of an individual component of the musical output. Physical sound producing channels were shared between "virtual" channels of the chordal component of the accompaniment, but such sharing did not take place between the various functional components of the accompaniment. Consequently, the hardware of such instruments involved substantial duplication of resources. At any point in time, a large number of output channels were necessarily unused. In addition, the output of each virtual channel was sounded in all cases, sometimes leading to a cluttered feeling on the part of the listener.